Charge-coupled semiconductor devices were first described in an article of similar title as published in the Bell System Technical Journal, Volume 49, Number 4, 1970, pages 587 to 593. Since that time much research has been conducted on CCD's to the present time wherein 64 kilobit single chip CCD memories have reached the commercial marketplace. (IEEE Spectrum, May 1978, page 36).
Memories are not the only use for CCD's, however. CCD's can be utilized in image sensing arrays and also for analog signal processors (Electronic Design 6, Mar. 15, 1976, page 70). However, the prior art does not show the use of CCD technology in analog to digital signal conversion wherein the actual conversion is accomplished directly on the CCD integrated circuit chip itself. Such a device would reduce the number of CCD and other type integrated circuit chips and increase signal to noise, amplification ratios, etc., due to the fact that the entire analog to digital conversion is done on one device.
As large scale integrated circuit techniques are extensive in the modern technology, construction of more than one such analog to digital conversion circuit on one chip is possible. Thus, coupling the CCD A/D conversion circuits together by transfer gate technology would lead to construction of multi-stage analog to digital conversion on a single LSI chip utilizing CCD technology.